What is the basic unit of structure and function in living organisms?

• A. The tissue
• B. The cell
• C. The organ
• D. The molecule

Answer: (B)

The basic unit of structure and function in living organisms is the cell. Cells are the smallest units that can carry out all life processes, from converting energy and building molecules to responding to the environment and reproducing. They contain specialized structures called organelles (like the nucleus, mitochondria, and ribosomes) that perform specific tasks necessary for the cell to live and work. Tissues are formed when many similar cells come together, organs are built from tissues, and molecules are the chemical building blocks that compose everything, but they don’t by themselves perform the full range of life processes. So the cell is the fundamental unit that both builds the body's structure and enables its functions.